Skillet materials: Properties and special features

Best skillet materials: properties and features

The essentials in brief

In ancient times, there was only one material for pans: iron. Thanks to new processing options, pans, and pots today are made of various metals. Unfortunately, you can hardly find websites on the internet that deal in detail with the properties of the various skillet materials.

We want to close this gap with this article. We promise that after reading this article you will know exactly why some materials work better for pans than others and where the pros and cons of the materials are.

In the first part of this article, we show which materials are available. If you want to go deeper, we recommend you to read the second part: Physics of the pan materials. 

In this part, we will take a closer look at the physical properties of the individual pan materials.

Comparison of skillet materials

Skillet Materials: Properties and Special Features

The following tables show the advantages and disadvantages of the individual pan materials

Copper skillet

Copper skillets for your kitchen
DescriptionCopper is a soft but durable material with very good thermal properties. The material oxidizes easily, but this can be prevented with proper care.
FormulaCopper sheet pieces are punched out and then "pressed" into shape.
Advantages- High thermal conductivity
- Very even heat distribution
- Reacts very quickly to heat changes
Disadvantages- Relatively heavy
- Very expensive
- Copper surface oxidizes and gets scratched quickly
- Due to its high thermal conductivity, the pan cools down very quickly
- No induction layer required without additional layer
- Pure copper pans give copper into the food.
Best useCopper lined with stainless steel.
Maintenance - Hand wash with non-abrasive agent
- Use of polishing paste to maintain the shine
Examples of copper skillets- Copper Chef Round Pan
- Copper Chef 10 Inch Diamond Fry Pan
- BulbHead 11198 Red Copper Square Pan

Aluminum skillet

DescriptionAluminum is cheap, weighs little and has good thermal properties. But it reacts with food. Most aluminum skillets therefore have a PTFE or ceramic coating. Pure aluminum skillets are barely available today.
Production method- Production by casting (hot aluminum is filled into a mold and cooled) - Production by pressing aluminum plates (deep drawing).
Advantages- Very favorable
- Good thermal properties.
Disadvantages- Reacts with food, especially if they are acidic
- Low density, resulting in poor heat capacity
- Deform the easiest
Best useAluminum lined with PTFE or ceramic.
Maintenance- Hand wash with detergent and soft side of the sponge
- Cleaning in the dishwasher shortens the life of the coating
Examples of aluminum skillets- Farberware Aluminum Nonstick 8-Inch, 10-Inch and 11-Inch Triple Pack Skillet Set
- Rachael Ray 12012 12.5" Deep Aluminum Skillet
- Hercules PA6500-FD Double Sided Skillet

Cast iron skillet

Cast iron skilllet
DescriptionCast iron consists of iron, carbon (more carbon than carbon steel, proportion> 2.06%) and a small proportion of other elements. Also available with enamel as a coating.
Production methodCast iron is heated to the point where it becomes liquid, then poured into molds and cooled.
Advantages- Relatively favorable
- The manufacturing process favors massive and dense pans that have a unique heat capacity
- Uniform heat distribution due to thickness (explanation for this under thermal conductivity )
- Uncoated cast iron gets a natural non-stick effect by baking.
Disadvantages- It takes a long time to heat
- Although very hard, but can be due to the brittleness in a fall on hard material or by strong cooling (cold water in a hot pan) get cracks
- rust susceptible to incorrect treatment.
Best useFor food that needs high heat but does not disintegrate easily.
Maintenance- Cast iron pans without enamel should be baked before first use (some pans are already branded by the manufacturer)
- Hand wash without detergent: Detergent removes the burnt-in grease remnants, which function like a non-stick coating. Do not leave in the water, otherwise rust will occur
- Enameled cast iron pans can be cleaned with detergent.
Popular cast iron skillets- Lodge Cast Iron Skillet, 10.25", Black
- Lodge 12 Inch Cast Iron Skillet
- Utopia Kitchen Pre-Seasoned Cast Iron Skillet - 12.5 Inch
- Lodge Seasoned Cast Iron 5 Piece Bundle

Carbon steel skillet

Carbon steel skillet electricskilletguide.com
DescriptionCarbon steel contains less carbon than cast iron. The carbon content is between 0.6 and 2%.
Production method Iron is processed into steel sheets in a multi-stage process. These circular pieces are then punched and brought into the wanted shape by pressing (thermoforming).
Advantages- Relatively inexpensive
- Very robust
- Natural non-stick effect through burn-in - Good heat capacity
- Less prone to breakage than cast iron.
Disadvantages- Relatively heavy (but lighter than cast iron pans)
- It takes a long time to heat up
- It takes a long time to have even heat
- Do not stand in the water, otherwise it will rust
- Soils may warp if the temperature difference is too great.
Best useFor food that needs high heat but does not disintegrate easily.
MaintenanceAre maintained just like uncoated cast iron pans.
Popular carbon steel skillets- Lodge CRS10 Carbon Steel Skillet
- Mauviel 3651.32 M'Steel Carbon Steel
- MINERAL B Round Carbon Steel Steak Fry Pan 9.5-Inch

Wrought iron skillet

DescriptionWrought iron has even less carbon content than carbon steel.
Production methodPig iron is extracted during hammering carbon and hammered in the form.
Advantages- Relatively inexpensive
- Very robust
- Natural non-stick effect through burn-in
- Good heat capacity
- Less susceptible to rust than carbon steel and cast iron
- Less prone to breakage than cast iron.
Disadvantages- Relatively difficult
- It takes a long time to heat up
- It takes a long time to get even heat.
Best useFor food that needs high heat but does not disintegrate easily
MaintenanceAre maintained just like uncoated cast iron pans.
Popular wrought iron skilletSOLIDTEKNICS US-ION 10-inch Wrought Iron Skillet –1/8-inch Seamless Cookware

Stainless steel skillet

Cooking egg on stainless steel skillet
DescriptionStainless steel is a steel to which chromium and nickel have been added. It can not rust and is hard and easy to care for. To improve thermal capabilities, an aluminum or copper plate is actually always used inside stainless steel pans.
Production methodUnalloyed steel is mixed with chromium and nickel. As with carbon steel, circular pieces are then punched out of steel sheets and deep-drawn into the pan shape.
Advantages- Stainless
- Easy to keep clean
- No reactivity with food
- Dishwasher safe
- In conjunction with copper or aluminum core very good thermal properties.
Disadvantages- Pure stainless steel pans have very poor thermal properties (but there is hardly any)
- Salt can attack stainless steel pans
- Poor non-stick effect due to incorrect operation
Best useWith proper operation and core made of copper or aluminum, stainless steel pans are suitable for almost anything.
Maintenance- Can also be cleaned in the dishwasher
- Steel wool should be avoided as it can scratch the surface.
Examples of stainless steel skillet- Pathfinder Stainless Steel Folding Skillet
- Hybrid Stainless Steel Nonstick Wok With Raised Honeycomb Pattern
- Cooks Standard NC-00233 Stainless Steel Stir Fry Pan

The basic principle of skillet materials

Cookware exists to transfer energy (ie heat) into the ingredients. We mainly know three ways to transfer energy to pans: gas, electrical resistance and induction.

Either for electric hobs or gas, the heat goes evenly : In a gas stove, the gas comes out of the burner at regular intervals and forms a flame ring.

In an electric range, we see an arrangement of the heating elements, so there is an even heat distribution, as evenly as possible. Nevertheless, there are places that are less hot than others.

The purpose of a pan is to transform this irregular distribution of heat into a uniform one. If the pan does not do that, some parts are hotter and some colder. The result: we cook food more than enough in some places, but still raw in others.

High-quality skillets, in addition to having a long shelf life and good workmanship, must also effectively transfer the heat energy to the ingredients.

Ideally, we would like to have a skillet that delivers even heat, can hold the heat well, and reacts quickly to heat changes of the heat source. We get this if we choose the best skillet materials.

Skillet materials thermal properties

These three properties depend on two factors of the skillet materials: thermal conductivity and heat capacity . Before we look more closely at the two factors, you should understand what hides behind the terms temperature and heat. Do not worry, this will only be a short excursion into physics lessons:

Temperature

In all substances that are above the absolute temperature zero, there is movement in the particles. We can measure this kinetic energy in the material as a temperature.

The higher the kinetic energy is, the more the particles of the material move, the higher the temperature of the material gets. Conversely, this means that the higher you heat a material, the greater the movement of the particles / atoms. Perhaps some of the memories of physics lessons at school will come up again.

Warmth

Heat, on the other hand, is a bit harder to define. In the scientific sense, it is a measure of the amount of energy that is transferred from one object to another object due to the temperature difference (hot flame transfers heat to a cold pan).

Heat does not actually describe the energy within an object, but only the energy exchange between two objects. The energy that exists within an object due to its temperature is actually what we call internal energy .

However, in normal usage, heat is useful for both transmitted and internal energy. This is how we have kept it largely in this article.



Skillet materials thermal conductivity

In an ideal world, the pan would have the same temperature at the surface at every point. Unfortunately, a material with this property does not exist. But there are materials that conduct heat better than others.

This property is actually the thermal conductivity of a material. Put simply, the thermal conductivity describes how easily a material absorbs heat energy and releases it again.

As soon as the flame or heating element comes into contact with the pan, the energy coming from the heat source goes then to the pan. This increases the inner energy of the pan, the pan heats up. The hot spots of the pan then transfer this energy to neighboring places that have a lower energy level (ie a lower temperature).

The higher the thermal conductivity of a material, the faster it heats up and the faster the heat dissipates to the parts of the material that are colder.

If one were to heat a plate of stainless steel directly on a gas flame, the area above the flame would become directly hot and the rest of the plate would warm up slowly.

The part of the steel that is not in contact with the flame, heats up from the direct area due to the heat flow. When the outer edges of the plate are hot, the points where the plate makes contact with the flame are extremely hot.

Heat Distribution Experimental:

In the picture below, this is how the heat distribution looks like from above. The white areas have the highest temperature, red is hot and blue is cool.

With a pan, of course, one would like to have as even heat as possible. Of course you could just continue to heat the skillet. However, this leads to pans with poor thermal conductivity that there are points where the pan is extremely hot and points where it is much colder.

Heat distribution in a just heated pan
Heat distribution in a just heated pan
Heat distribution in a longer heated pan
Heat distribution in a longer heated pan

One solution to this problem is to use thicker material.

A thicker plate Stainless steel has a different temperature pattern at the top than a thinner piece of stainless steel. 

The distance between the gas flame and the surface of the plate is larger, the heat energy must go from the bottom of the plate to the surface. This results in a more even heat at the surface of the stainless steel plate.

Results:

The figure above shows that with a thicker plate, although we measure less heat  at the surface at certain points, the heat distribution is much more even.

Low thermal conductivity also means that a lot of energy has to be put into the bottom of the plate to bring the top up to a higher temperature.

A pan of material with poor thermal conductivity so takes longer to get to cooking temperature.

In addition, material with poor thermal conductivity takes longer to respond to temperature changes.

For most types of cooking, it is beneficial to have cookware that heats up quickly, distributes the heat evenly, and reacts quickly to changes in temperature. 

These requirements are met by materials with high thermal conductivity because they conduct heat quickly.

This leads to a fast response time with temperature changes and a uniform distribution of heat energy.

This table shows the most common materials for pans and their thermal conductivity. The data comes from engineersedge.com 

Conclusion:

For aluminum, however, we notice that most pan manufacturers do not use pure aluminum, but rather alloys. These alloys have the advantage of being more robust and less susceptible to corrosion. However, these alloys usually suffer from thermal conductivity.

This means that aluminum pans in reality conduct worse, but still have a much better thermal conductivity than steel or iron.

Unlike aluminum, almost pure copper is used for copper pans.

Thermal conductivity in practice

The theory must also exist in practice. Therefore, we compared a cast-iron pan with a stainless steel pan with copper bottom. The bottom of the pan is about the same thickness.

In both we have added a thin layer of flour using a sieve. Then both pans were heated on a wok burner with an extremely high power (Roaring Dragon, 24 kW).

Exactly where the flour is the darkest at the end, is the burner:

Skillet materials: Thermal conductivity in practice

In the cast iron pan, the spot under the burner heats up extremely, while the heat hardly dissipates to the outside.

In the pan with copper bottom, the heat concentrates in the middle, but takes also direction to the outside. The heat distribution is much better with this pan.

Of course, this is an extreme example, with such strong burners is hardly cooked in a normal kitchen.

Heat capacity

we define the amount of internal energy storage in a material as the heat capacity of the material.

Attention: This is not the same as the temperature. For example, one kilogram of water at 50 degrees Celsius contains more internal energy than one kilogram of steel at 50 degrees Celsius.

While thermal conductivity describes the ability of a material to absorb energy. The heat capacity refers to the amount of energy in need to raise or lower the temperature of the material.

While water requires a lot of energy to increase internal energy, the internal energy of metals can go higher much more easily.

The heat capacity of a material is proportional to its mass. A 2 kg piece of stainless steel has twice the heat capacity of a 1 kg piece of stainless steel.

This means that materials with higher heat capacity take longer to heat up but at the same time have high internal energy when heated. If energy is removed from the material, the temperature will be less than that of a material with low heat capacity.

Skillet Materials with High Heat Capacity:

Applied to the example of water and metals. It takes a lot of energy to increase the temperature of water, but the water also keeps that energy much longer. Metals increase their temperature faster with the same energy input, but cool much faster than water.

We often mention cast iron as a material with high heat capacity. The specific heat capacity (the heat capacity for a given mass) of cast iron is only half of the specific heat capacity of aluminum. However, cookware coming with cast iron usually has a much higher mass than aluminum, so that the heat capacity is much higher.

Many manufacturers mention the thickness of the metals of their cookware (eg 3 mm aluminum). However, the heat capacity is a function of the material mass, so the density must be known to compare cookware with each other.

Heat capacity of skillet material

When the specific heat capacity is multiplied by the density, it is found that the heat capacity per unit of steel, cast iron and copper 1.5 is as large as that of aluminum. It follows that an aluminum pan must be 1.5 times as thick as pans of the other materials to achieve the same heat capacity (if all other dimensions are the same).

In a nutshell: thermal diffusion

Anyone who has paid attention will notice that not only the thermal conductivity is responsible for the rate of heating . But also the heat capacity is responsible of the uniformity of the heat distribution.

However, there is one unit that tells us at which speed the heat is spreading in the material: the thermal diffusivity. This is simply the division of  the thermal conductivity by the heat capacity per unit (i.e. the results from the table above).

This is how the materials compare:

Thermal diffusivity

The table shows that aluminum and copper are the best materials in terms of heat dissipation. However, there is another factor that should not be overlooked when buying cookware:

Reactivity

When it comes to the characteristics of cookware materials, we must not only focus on the thermal properties of copper and Co. We have also to make sure the pan does not react with food. Unfortunately, copper and aluminum react very easily to food. 

If copper consumption is high or in large quantities, liver, stomach or kidney problems can follow. Aluminum also carries health risks and is even suspected of favoring Alzheimer’s. However, there is still no study that could establish a direct relationship.

Unfortunately, the least reactive material of skillet materials, stainless steel, also has the worst thermal conductivity.

Iron also reacts with food, but iron is an important element in the body. Therefore, the inclusion of iron on cookware may even have a health-promoting effect.

There’s a way to get the best of both worlds. By combining stainless steel and copper or aluminum we create pans that have low reactivity and good thermal conductivity. Pure aluminum and copper pans are barely there, due to the health risks mentioned above.

The best skillet materials combinations

The list below shows what we consider to be the best combinations when it comes to good thermal properties and reactivity. However, carbon steel pans and cast iron pans have definitely earned a place in the kitchen because of their sturdiness and their natural non-stick ability. For the individual materials, there is more below:

  1. Copper with stainless steel lining.
  2. Stainless steel pan with copper core / copper bottom.
  3. Stainless steel with aluminum core.

Although cast iron pans and pans made of carbon steel (forged or rolled iron pans) are in last place in this table, they are indispensable in the kitchen. Both types of pans store heat energy very well (due to the mass and density of the materials), cast iron pans even better than iron pans. But cast iron pans are heavier again.

They are therefore more suitable than any other pans when it comes to delivering consistent and high heat to the food. In addition, iron pans over time obtain a natural coating by the so-called burn-in .

There are other combinations. The coated pans were deliberately not treated here.

If you have questions about this article or individual materials, you can simply leave a comment below this article. We hope that the article will help you in choosing your next pan.

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